linux-kernel - [PATCH] drm/msm/devfreq: Insert missing null check in msm_devfreq

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Date:   Wed, 17 Nov 2021 12:11:34 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     phone-devel@...r.kernel.org
Cc:     ~postmarketos/upstreaming@...ts.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Pavel Dubrova <pashadubrova@...il.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/msm/devfreq: Insert missing null check in msm_devfreq_idle

msm_devfreq_init only initializes the idle_work hrtimer when it succeeds
to create a devfreq instance (devfreq support is optional), yet
msm_devfreq_idle is called unconditionally from retire_submit and queues
work on it.  We're seeing:

    [    2.005265] adreno 1c00000.gpu: [drm:msm_devfreq_init] *ERROR* Couldn't initialize GPU devfreq

Followed by a pagefault in:

    [   16.650316] pc : hrtimer_start_range_ns+0x64/0x360
    [   16.650336] lr : msm_hrtimer_queue_work+0x18/0x2c

Moments later.  Just like msm_devfreq_active, check if the devfreq
instance is not NULL before proceeding.

Fixes: 658f4c829688 ("drm/msm/devfreq: Add 1ms delay before clamping freq")
Reviewed-by: Konrad Dybcio <konrad.dybcio@...ainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
---
 drivers/gpu/drm/msm/msm_gpu_devfreq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 8b7473f69cb8..ae3309ff96e4 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -227,6 +227,9 @@ void msm_devfreq_idle(struct msm_gpu *gpu)
 {
 	struct msm_gpu_devfreq *df = &gpu->devfreq;

+	if (!df->devfreq)
+		return;
+
 	msm_hrtimer_queue_work(&df->idle_work, ms_to_ktime(1),
 			       HRTIMER_MODE_ABS);
 }
--
2.34.0